The invention pertains generally to rear projection screens and, more specifically, to rear projection screens useful in display equipment for providing light transmission over a widened viewing angle.
The advent of large screen projection television systems has been accompanied by an increasing interest to improve the optical properties of rear projection screens with respect to providing a high resolution, high gain, uniform intensity distribution of light over a horizontally widened viewing angle, with good ambient light rejection and minimal hot spot formation at the center of the screen. Numerous screen designs have been developed in an effort to optimize these properties, including various surface and bulk treatments of the screen employed separately and in different combinations. Surface treatment has included (1) embossing the screen surface with lens elements of various configurations for light refraction and diffusion, and also for light focusing; and (2) applying one of several light diffusing coatings to the screen surface, e.g., a powdered inorganic material in an organic binder. Bulk treatment has included the employment of (1) a light diffusing semi-transparent solid material, such as a natural or synthetic wax, fabricated as a sheet or plate; and (2) a crystalline polymer material fabricated as a sheet or plate. While screen designs of the prior art have met with varying degrees of success in the achievement of the sought after optical performance, none is found to be entirely adequate, particularly when limited projection light is available. Further, all of the relatively good performing screens are found to be quite costly to manufacture.